1. Field of the Invention
The invention is concerned with methods and apparatus for high-shear mixing and reacting of materials involving a chemical and/or a physical action(s) or reaction(s) of a component or between components.
2. Review of the Prior Art
Apparatus for materials processing consisting of coaxial cylinders that are rotated relative to one another about a common axis, the materials to be processed being fed into the annular space between the cylinders, are known, as shown for example, in U.S. Pat. No. 5,370,999, issued 6 Dec. 1994 to Colorado State University Researeh Foundation, and U.S. Pat. No. 5,340,891, issued 23 Aug. 1994 to Nippon Paint Co., Ltd. My U.S. Pat. No. 5,279,463 (issued 18 Jan. 1994); U.S. Pat No. 5,538,191 (issued 23 Jul. 1996); and pending U.S. Pat. No. 6,471,392 (issued Oct. 29, 2002) disclose methods and apparatus for high-shear material treatment, one type of the apparatus consisting of a rotor rotating within a stator to provide an annular flow passage comprising a flow path of uniform radial dimension along its length containing a high-shear treatment zone in which free supra-Kolmogoroff eddies are suppressed during passage of the material therethrough. In another type of the apparatus the passage spacing at one location on its circumference is smaller than in the remainder of the zone to provide a subsidiary higher-shear treatment zone in which free supra-Kolmogoroff eddies are suppressed.
Couette developed an apparatus for measuring the viscosity of a liquid consisting of a cylinder immersed in the liquid contained in a rotating cylindrical vessel, the viscosity being measured by measuring the torque that was thus applied to the cylinder. It was found that a linear relationship was obtained between the viscosity measurement and the angular velocity of the rotor surface up to a certain value beyond which the linear relationship broke down. This phenomenon was investigated by G. I. Taylor who showed that when a certain Reynolds number was exceeded the previously stratified flow in the annulus between the two cylindrical surfaces became unstable and vortices appeared, now known as Taylor vortices, whose axes are located along the circumference of the rotor parallel to its axis of rotation and which rotate in alternately opposite directions. The conditions for the flow to be become unstable in this manner can be expressed with the aid of a characteristic number known as the Taylor number, depending upon the radial width of the annular gap, the radius of the rotor and its peripheral velocity. I have found, as described in my pending U.S. application Ser. No. 09/802,037 (filed Mar. 7, 2001), the disclosure of which is incorporated herein by this reference, that when using such apparatus for the types of process where thorough mixing is required, the presence of the Taylor vortices inhibits the action or reaction desired since the material to be treated becomes partially entrapped in the vortices, whereupon mixing is impaired and is required to be replaced by much slower diffusion processes.